Senior Member

It's a difficult question to answer, as the phrase is poetic and can rarely be translated literally. Even among the non-literal translations, you may find a number of different (and sometimes opposing) meanings.

I think along with the "swing, swing, swing" in the song, the notes here probably represent nothing more than the "old song" of the "old affair", the old love song with the lover he's lost. The notes are old, they bend, they fold, / and so does he to a new love. So now there will be a new song with new notes. Simple metaphor. Love is a song you sing.

Banned

Banned

I see a reference to a ribbon-bound bundle of love-letters.
The letters which were sent have been stored away in the envelopes they arrived in and bound up tightly, and if you take them out and read them they readily bend and fold into the shapes they have been pressed into by time.